Release v0.21.0

[lidel]

This is me following the process from https://github.com/ipfs/boxo/blob/main/RELEASE.md#release-process (minus creating issue with the checklist, I'm doing the checklist below).

Initial impression: we could simplify a lot of manual labor by switching to release-please, and doing patch releases if needed by hand, rather than doing everything by hand. We will discuss once this one ships the old way.

---

• [x] Create a release branch called release-vX.Y.Z and push it
  • Use master as base if Z == 0
  • Use release as base if Z > 0
• [x] Tidy the changelog and push any changelog changes to release-vX.Y.Z
• [x] Create a draft PR merging release-vX.Y.Z into release
  • [ ] Name it "Release vX.Y.Z"
  • [ ] Reference this release issue
• [ ] If Z > 0, then cherry-pick the necessary commits from master into release-vX.Y.Z using git cherry-pick -x <commit>
• [x] Ensure Boxo tests are passing
• [x] Ensure Kubo tests are passing
  • [x] Go to Kubo dir and run go get github.com/ipfs/boxo@<commit_hash> using the commit hash of the release-vX.Y.Z branch
  • [x] Run go mod tidy in repo root and in docs/examples/kubo-as-a-library
  • [x] Commit the changes and open a draft PR in Kubo
  • [ ] Name the PR "Upgrade to Boxo vX.Y.Z"
  • [x] Paste a link to the Kubo PR in the Boxo PR, so reviewers can verify the Kubo test run
  • [x] Verify the CI passes (https://github.com/ipfs/kubo/pull/10444)
• [x] Add a commit in release-vX.Y.Z bumping the version in version.json to vX.Y.Z
• [x] Add a "release" label to the Boxo PR
• [x] After the release checker creates a draft release, copy-paste the changelog into the draft
• [ ] Wait for approval from another Boxo maintainer
• [x] Merge the PR into release, using "Create a Merge Commit", and do not delete the release-vX.Y.X branch
  • [x] Verify the tag is created
• [x] Announce the release
  • [x] Click this link to start a new Discourse topic
  • [x] Update vX.Y.Z in the title and body
  • [x] Create the topic
• [x] Create a PR merging release into main
  • [x] Name it "Merge release vX.Y.Z"
  • [ ] Wait for approval
  • [ ] Merge it using "Create a Merge Commit", and do not delete the release branch
• [ ] Update the Kubo PR to use the newly released version, mark it as "Ready for Review", get approval, and merge into Kubo

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 63.57143% with 51 lines in your changes missing coverage. Please review.

Project coverage is 59.81%. Comparing base (980447e) to head (4eec0e4).

@@             Coverage Diff             @@
##           release     #622      +/-   ##
===========================================
- Coverage    59.83%   59.81%   -0.02%     
===========================================
  Files          239      238       -1     
  Lines        29961    29984      +23     
===========================================
+ Hits         17928    17936       +8     
- Misses       10419    10431      +12     
- Partials      1614     1617       +3     

Files	Coverage Δ
...ernal/providerquerymanager/providerquerymanager.go	87.45% <100.00%> (-1.35%)	:arrow_down:
bitswap/client/internal/session/session.go	91.15% <100.00%> (+0.09%)	:arrow_up:
routing/http/contentrouter/contentrouter.go	50.56% <63.15%> (+1.42%)	:arrow_up:
examples/car-file-fetcher/main.go	38.88% <38.88%> (ø)

... and 15 files with indirect coverage changes

[github-actions[bot]]

Cutting a Release (when not on ["main"])

This PR is targeting release, which is not any of ["main"]. If you wish to cut a release once this PR is merged, please add the release label to this PR.

[github-actions[bot]]

Suggested version: v0.21.0

Comparing to: v0.20.0 (diff)

Changes in go.mod file(s):

(empty)

gorelease says:

# diagnostics
go.mod: the following requirements are needed
    go.opentelemetry.io/otel/exporters/jaeger@v1.14.0
Run 'go mod tidy' to add missing requirements.
required module github.com/microcosm-cc/bluemonday@v1.0.1 retracted by module author: Retract older versions as only latest is to be depended upon

# summary
Suggested version: v0.20.1

gocompat says:

Your branch is up to date with 'origin/release'.

Cutting a Release (and modifying non-markdown files)

This PR is modifying both version.json and non-markdown files. The Release Checker is not able to analyse files that are not checked in to release. This might cause the above analysis to be inaccurate. Please consider performing all the code changes in a separate PR before cutting the release.

Automatically created GitHub Release

A draft GitHub Release has been created. It is going to be published when this PR is merged. You can modify its' body to include any release notes you wish to include with the release.

[lidel]

Ok, took some notes in https://github.com/ipfs/boxo/issues/623 on the process, but no blockers, all green.

Shipping and bubbling up to kubo/rainbow/someguy, so we can tag releases of the last two next week.